4391921 has 2 divisors, whose sum is σ = 4391922. Its totient is φ = 4391920.

The previous prime is 4391911. The next prime is 4391923. The reversal of 4391921 is 1291934.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3312400 + 1079521 = 1820^2 + 1039^2 .

It is a cyclic number.

It is not a de Polignac number, because 4391921 - 2⁶ = 4391857 is a prime.

It is a Sophie Germain prime.

Together with 4391923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (4391923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2195960 + 2195961.

It is an arithmetic number, because the mean of its divisors is an integer number (2195961).

Almost surely, 2^4391921 is an apocalyptic number.

It is an amenable number.

4391921 is a deficient number, since it is larger than the sum of its proper divisors (1).

4391921 is an equidigital number, since it uses as much as digits as its factorization.

4391921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 29.

The square root of 4391921 is about 2095.6910554755. The cubic root of 4391921 is about 163.7639003020.

The spelling of 4391921 in words is "four million, three hundred ninety-one thousand, nine hundred twenty-one".